The present disclosure relates to a fuel supply device used for supplying fuel stored in a fuel tank to an internal combustion engine.
A known vehicle fuel supply device may generally comprise a pump unit, a cover member and a connection shaft. The pump unit may include a fuel pump and a cup-shaped reserve tank for accommodating the fuel pump. The cover member may be arranged on an upper side of the pump unit. The connection shaft may connect the pump unit and the cover member. The cup-shaped reserve tank of the pump unit may have a bottom wall and an upper opening. The pump unit may further include a pump case for accommodating the fuel pump. The pump case may be disposed within the reserve tank. The connection shaft may protrude upwards from the reserve tank. The cover member may be movable in the vertical direction along the connection shaft while being urged upwards with respect to the pump unit by an elastic member. When the fuel supply device is arranged inside the fuel tank and the cover member is attached to the upper wall of the fuel tank, the urging force of the elastic member may press the pump unit against the bottom wall of the fuel tank, so that the fuel supply device may be fixed in position within the fuel tank.
With the above known fuel supply device, vibrations generated during the operation of the fuel pump may be transmitted in the following order: the fuel pump, the pump case, the reserve tank, and the bottom wall of the fuel tank, or in the following order: the fuel pump, the pump case, the reserve tank, the connection shaft, the cover member, and the upper wall of the fuel tank. Therefore, the vibrations transmitted from the fuel pump may generate noise.
Japanese Laid-Open Patent Publication No. 2004-204847 (also published as US2005/0058556) discloses a vibration isolating fuel pump assembly in which an electric fuel pump fixed to a retainer (corresponding to the pump case) is accommodated in a cup-shaped reservoir (corresponding to the reserve tank) that includes a bottom wall and an upper opening. The retainer is connected to the reservoir via elastic support elements each comprising an elastic connection element a flexible leg portion. The elastic connection element is curved in an S-shape toward the reservoir inner wall. The flexible leg portion extends in the vertical direction from the elastic connection element.
Japanese Laid-Open Patent Application No. 2002-295327 discloses a fuel supply device in which a fuel pump fixed to a unit housing (corresponding to the pump case) is accommodated in a cup-shaped sub tank (corresponding to the reserve tank) that includes a bottom wall and an upper opening. The unit housing is connected to the sub tank via elastic support elements each comprising a support portion formed of a thin resin plate. The support portion extends substantially in the circumferential direction along the outer circumferential surface of the unit housing. The support portion has opposite ends in the extending direction. One of the opposite ends of the support portion is fixed to the outer peripheral surface of the unit housing, and the other of the opposite ends is fixed to the inner peripheral surface of the sub tank.
In both Japanese Laid-Open Patent Publication No. 2004-204847 and Japanese Laid-Open Patent Application No. 2002-295327, opposite ends of each elastic support element are firmly fixed to the pump case and the reserve tank, respectively. Therefore, only an intermediate portion of the elastic support element located between a connection portion including the one end connected to the pump case and a connection portion including the other end connected to the reserve tank can elastically deform for adsorbing vibrations. If an attempt is made to increase the maximum limit of the amplitude of the elastic deformation in order to absorb vibrations having larger amplitudes, it may be necessary to increase the connection distance between the connection portion connected to the pump case and the connection portion connected to the reserve tank. However, increasing the connection distance without changing the capacity of the fuel pump (i.e., the size of the fuel pump) may need to increase the size of the reserve tank, which is rather undesirable in these days where a reduction in size is required.
Therefore, there has been a need in the art for a technique of efficiently absorbing vibrations without need of enlarging the size of the fuel pump and/or the size of the reserve tank.